1，能够用route命令暂时改动：

route add default gw <gateway ip>

2, 通过改动/etc/sysconfig/network 文件永久改动：

脚本：

#!/bin/sh
#configure default gw
#   $1 is ip of gateway

defgw=$1
sed -i "s/NETWORKING.*/NETWORKING=yes/" /etc/sysconfig/network
sed -i "s/HOSTNAME.*/HOSTNAME=`hostname`/" /etc/sysconfig/network
echo "GATEWAY=$defgw" >> /etc/sysconfig/network
service network restart

事实上终于的/etc/sysconfig/network的格式是：

~]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=c902f02x44
GATEWAY=60.0.0.202

然后重新启动network服务：service network restart